Silver halide film cameras capture scenes on a light sensitive emulsion. At the time of capture, it is useful to provide information of scene content, such as date, time or a descriptive embodiment. Kodak Autographic series of cameras, produced from 1914 to 1927 used a thin metallic sheet over the film to permit pressure induced writing on a sheet of silver halide film. The operator could not see the image they had written.
Many cameras have a battery powered clock, and a small array of light emitting diodes that can write the date/time information onto the film itself. U.S. Pat. No. 5,715,486 discloses a camera having a small keyboard for typing characters into a memory, showing those characters on display and writing the character over an image using the small array of light emitting diodes. These systems require an interface to the keyboard, and a display to observe typed characters. The operator is limited to characters on the keyboard.
Drawings can be displayed using cathode ray tubes, which require a large amount of power, and continuous electronic drive. Alternatively, drawings can be displayed by twisted nematic polarizing displays which require complex drive electronics. Writing can be detected; stored in a memory plane and continually written to such displays to create a writable tablet.
U.S. Pat. No. 4,525,032 discloses a display that uses cholesteric memory material that is pressure, electrical field and heat sensitive. Writing on the surface of such a display causes a change in optical properties of the bi-stable material. A high voltage pulse can be used to erase such a display. The patent further discloses means to sense the pen's position during writing so as to digitize the position of the pen during writing. Such a display has the advantage of showing erasable drawings, and digitizing said drawings.
Digitizing a stylus position using spaced, conductive sheets is disclosed in U.S. Pat. No. 5,670,755. Two conductive sheets are spaced apart with spacer beads and pressure is applied to bring the two sheets in contact at a given position. Two sets of orthogonal oriented conductors are used to find the resistive potential between each contact and the contact position. Alternatively in the patent, a potential on a stylus is used to find a contact position on the sheet.
A camera with image display and text information is disclosed in commonly-assigned U.S. Pat. No. 5,689,742. In that patent, a powered display shows a captured scene. A touch sensitive layer over the display senses contact position of a stylus, digitizes the position, stores those coordinates in a memory. The information is displayed over the image on the camera display. The patent requires the use of a pixelated, powered and electronically driven display to show the drawing to an operator.